(a) Technical Field
The present invention relates to a clutch torque control system. More particularly, the present invention relates to a clutch torque control system of a hybrid electric vehicle, which performs an engine rotational speed control in a power generation system including an engine, a motor-generator, and a clutch for controlling connection and disconnection between the engine and the motor-generator.
(b) Background Art
Output power of an engine of a vehicle is transmitted to wheels through a clutch, a transmission, and a deferential gear.
During start-up of the engine or during low-speed driving where the engine rotational speed is low, an irregular rotation of the engine is directly transmitted to the wheels, thus degrading driving performance.
Japanese Patent No. 2900667 discloses a slip lock up controller, in which a clutch is controlled in a half-clutch state during start-up or during low-speed driving.
According to the above slip lock-up controller, a slip amount (Δn) may be defined by the following formula 1.Δn=clutch input rotational speed−clutch output rotational speed   [Formula 1]
According to Japanese Patent No. 2900667 as described above, as engine torque vibration, when the slip amount (Δn) is 0 during clutch engagement, is directly transmitted to the transmission, a driver may feel discomfort. The Japanese Patent No. 2900667 as described above does not discuss or suggest that a change in the slip amount (Δn) causes a change in friction coefficient (μ) of the clutch, and that accordingly the transfer torque is changed.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.